Many problems after SP2 install--am I looking at a complete reinst

OK-I am not able to access Windows Update site- receive error 0x800AO1AD.
Have attempted to reinstall MSXML.DLL files, no help.

Can no longer access system restore, logon takes forever and there are
problems when I shut down (takes a long time and sometimes hangs at "saving
your settings"

If I am looking at a complete reinstall, can anyone tell me what to avoid so
this mess does not happen again??

Thank you in advance!

Me too. It freezes, games are SLOW, and the entire
computer is a comical stuttering mess now. I also have
the LONG shutdown procedure. Sad. I should uninstall
this 'service' pack and do an entire restore, but then I
lose all of my installed programs. Oh well. Maybe MS will
make a patch for this service pack 2. I hope so, at least.